This invention relates to rotary sprinklers and, specifically, to pop-up rotary sprinklers of the type which include generally a sprinkler body, a discharge orifice and a rotatable distributor mounted on the sprinkler body downstream of the orifice. The orifice and distributor assemblies are typically secured to an inner stem which is movable between a retracted or inoperative position and an extended or operative position. Such sprinklers often make use of distribution grooves on the rotatable distributor which are arranged so that a stream impinging on the grooves will cause the distributor to rotate about a center axis of the sprinkler body. See, for example, U.S. Pat. Nos. 4,471,908 and 1,821,579.
It is also known to utilize in connection with such sprinklers interchangeable arc or other shaped nozzles in order to permit easy adjustment of the degree of coverage of the discharged stream, while maintaining a constant flow or precipitation rate to the watered areas. Typically, these nozzles comprise orifice plates which have a central hole for receiving a shaft which supports the distributor above the nozzle. The orifice itself is generally radially outwardly spaced from the shaft hole in the orifice plate. Representative examples of this type of construction are described in U.S. Pat. Nos. 4,932,590; 4,842,201; in the previously mentioned 4,471,908, and in 3,131,867.
It will be appreciated, however, that for a constant flow rate and constant degree of arcuate coverage, the width of the orifice necessarily decreases with radial distance from the center axis. In other words, since the arcuate length necessarily increases as the orifice is moved away from the radial center, the width of the slot necessarily must decrease to maintain constant the overall orifice area and, hence, flow rate. The narrower the orifice, however, the greater tendency for the orifice to clog with dirt or other debris. It is therefore desirable to locate the orifice as close as possible to the radial center to minimize the arcuate length and thus maximize the orifice width. This, of course, permits larger size contaminants to pass through the orifice and thereby reduces potential clogging. In the best of circumstances, therefore, the orifice slot will actually border on, or be defined partially by, the distributor supporting shaft.
There have been a few sprinkler constructions where the distributor shaft itself defines part of the nozzle discharge orifice. See U.S. Pat. Nos. 4,353,506 and 4,261,515. One significant disadvantage of having the shaft form part of the discharge orifice, however, is that the discharged stream will impinge directly on the shaft/distributor interface. In those instances where a seal is employed at that interface, the direct impingement of water on the seal can lead over time to seal damage and/or failure. Seal integrity is particularly critical in the present sprinkler assembly which includes a viscous brake within the distributor housing for slowing the rotational speed of the distributor. In this particular construction, if the distributor seal is damaged, the viscous fluid may leak out of the distributor, thereby rendering the viscous brake inoperative.
It is therefore the principal object of the present invention to take advantage of the larger discharge orifice made possible by locating the orifice directly at the center shaft while at the same time, preventing stream impingement on the distributor shaft seal.
This object is achieved by providing a deflector on the shaft immediately adjacent and downstream of the discharge orifice which directs the discharged stream away from the seal and substantially tangentially onto the stream distributing grooves of the rotatable distributor.
As mentioned above, the preferred sprinkler construction in accordance with this invention incorporates a viscous brake within the distributor. There is a need for easy yet effective filling of the viscous brake chamber and, to do this, it is necessary to permit air in the chamber to escape during filling.
It is therefore another object of the invention to provide an improved viscous brake within the distributor assembly by providing an air vent hole in the distributor housing to permit escape of air during filling of the viscous brake chamber, as well as an associated seal arrangement to prevent subsequent leakage through the vent hole.
This second object is achieved by forming a pair of radially extending holes in the distributor housing, substantially diametrically opposed to each other. One hole is used for filling the viscous brake chamber, the other for venting air as the chamber is filled. An O-ring type seal is used to close the two holes, and the seal is pressed into engagement with the holes by an adjustable distributor cap, as explained in greater detail below.
Thus, in accordance with one aspect of the invention, there is provided a rotary sprinkler having a sprinkler body, a rotatable distributor assembly and a nozzle assembly wherein the rotatable distributor assembly and nozzle assembly are axially fixed in spaced relationship with respect to each other by means of a shaft, and wherein the distributor assembly includes stream distribution surfaces, the improvement comprising a discharge orifice in the nozzle assembly at least partially defined by the shaft and a deflector on the shaft between the discharge orifice and the rotatable distributor assembly for deflecting a stream of fluid emanating from the discharge orifice onto the stream distribution surfaces.
In another aspect, the invention provides a pop-up rotary sprinkler comprising a sprinkler body, a rotatable distributor and nozzle assembly mounted in the sprinkler body for movement between inoperative retracted and operative extended positions in response to fluid pressure within said sprinkler body, said assembly including a rotatable distributor supported at an upper end portion of a shaft and a nozzle assembly surrounding a lower end portion of the shaft, the distributor having a plurality of water distributing grooves, and the nozzle assembly including a discharge orifice having a peripheral surface at least a part of which is defined by a peripheral surface of the shaft; a deflector mounted on the shaft downstream of the discharge orifice and upstream of the distributing grooves and adapted to direct water emanating from the discharge orifice to the distributing grooves.
Other objects and advantages of the present invention will become apparent from the detailed description which follows.